US788813A - Process of treating fine ores. - Google Patents

Description

UNITED STATES Patented May 2, 1905.

PATENT OEEIcE,

DAVID BAKER AND WILLIAM W. HEARNE, OF WAYNE, PENNSYLVANIA.

PROCESSOF TREATING FINE ORES;

SPEGIFICATIGN forming part of Letters Patent No. 788,813, dated May 2, 1905.

Application filed February 3, 1905. Serial No. 2%,986.

To (ZZZ whom, it may concern:

Be it known that we, DAVID BAKER and TIL- LIAM W. H nAENn,citizens of the United States, and residents of Wayne, county of Delaware, State of Pennsylvania,have in vented a new and useful Process of Treating Fine Iron Ores, of which the following is a specification.

Our invention relates to a new and useful process of treating fine ores or residuessuch as magnetic concentrates or the iron ore variously known as pyrites residuum, pyri-tes cinders, purple ore, and blue billy to render the same suitable for blast-furnaces.

The object of our invention is to render valuable for the manufacture of iron the large and important classes of iron-bearing ores that are now practically valueless on account of the finely-divided state of such ores or on account both of their large sulfur content, and their finely-divided state.

With respect to the fine ores in which sulfur is not present in objectionable quantities, but where the ore is so finely divided as to cause loss in the smelting and expensive slips and irregularproduct, it is necessary to change the mechanical characteristic of this ore before the same can be advantageously used in blast-furnaces. Various methods have been employed to treat such ore to render it suitable for blast-furnaces for example, the mixing therewith of lime or clay or similar materials, grinding the same together, and moisteningthe mixture sufficiently to render it pasty, so that it may be briqueted. Another method is to mix with the ore salt or slag or other fluxing material and then to burn the mixture to agglomerate it. It will be obvious that a process which will agglomerate this fine ore without the admixture therewith of a flux or hinder will result in enormous saving of time and expense when large quantities of the ore are so treated, for it is well known that the admixture with the ore of a fluxing material requires the transportation very often of said flexing material to the place where the ore is to be treated, the grinding or otherwise preparing of the fluxing material, and the proper mixing of the same with the ore, which admixture will vary to suit different qualities of the ore. It will also be obterials of each particle of ore-dust.

vious that the use of said fluxing material will involve a substantial increase of fuel consumption in the subsequent smelting operation, due to the extra heat required to smelt these additions of flux, all of which implies the consumption of time and money and the employment of special apparatus.

Our process obviates the necessityof mixing a separate fluxing material with the ore. Instead of this it utilizes the constituent ma- These particles contain, intimately combined with the iron oxid, such impurities as alumina, silica. lime, magnesia; &c. The mass of oredust is subjected to a heat which shall melt these impurities, forming a fusible mass with the oxid of iron, or the fusion may be con fined to such parts thereof as lie upon and near the surface of the particles until said surfaces become soft or semiplastic and sticky, thereby causing the particles to adhere one to another. The degree of heat need not be such as would be necessary to melt the iron oxid alone, since the combination thereof with the other impurities mentioned, in accordance with a well-known metallurgical law, will melt at a much lower temperature than each would separately. The rolling agitation of the mass causes the formation of lumps or nodules of suitable size for blast-furnace treatment. With respect to the fine ores which have a large sulfur content it is also necessary to remove the excess of sulfur to render the subsequent smelting process simpler and cheaper, for thesmelting operation being carried on in a reducing-atmosphere will only partially remove this very objectionable impurity. It is then also important to agglomerate this fine dusty material to prevent loss in smelting and expensive slips and irregular product which, as is well known, result when smelting fine ore.

We are well aware that it is not new to desulfurize ore; but we believe we are the first to employ the process which consists in agitating the material at a temperature low enough to prevent the sulfid of iron from melting and at the same time maintaining strongly-oxidizing conditions. The agitation of the mass during the process of desulfurization is of the utmost importance, since it serves to bring every particle of said mass into contact with the atmosphere, upon which condition the efficiency of the desulfurization depends. When the desulfurization of the mass is complete, by increasing the temperature to which said mass is subjected theprincipal metallic oxid will fuse with the other oxids contained in said ore. This will result in an agglomeration of the mass, and by the agitation thereof the same will be broken into sizes suitable for furnace use.

It is Well known that sulfid ores melt into clinker very easily; but thismelting or clinke ering will prevent the escape of the sulfur, so that it is important that the-desulfurization be carried on at a low temperature an d, finally, when the desulfurization iscomplete, to depend on the increased temperature to-cause the impurities which, as above. stated, are al ways present in such materials to furnishthe flux to agglomerate the iron oxid with which such impurities are intimately mixed.

By our process we not only eliminate the sulfur contained in the ore, but we also secure without the adding of slag or any other fluxing material the agglomeration of the ore in a state suitable for blast-furnace treatment.

We prefer to use for our process a long ro tary kiln, such as is used in the manufacture of cement, for we can, by charging the material at the cold end, complete the desulfurization before the material reaches the zone of highest temperature, where the clinkering takes place. It would be possible, however, to use a shorter kiln and vary the tempera.- ture as required by the process. With respect to. some materials or ores our process may be facilitated by moistening the ore before charging. it into the kiln.

What we claim is 1. The process of agglomerating fine iron ores or residues,.which consists in subjecting the same to atemperature which shall cause the particles thereof, due to the impurities contained therein, to fuse sufficiently to become semiplastic and sticky, and to agitate, by rolling the mass, when in the semiplastic state.

2. The process of desulfurizing and agglomerating fine iron ores or residues, which consists in eliminating the sulfur by means of an oxidizing atmosphere. at a temperature best suited for that purpose, and then moving the mass into a temperature which shall cause the particles thereof, due to the impurities contained therein, to fuse sufficiently to become semiplastic and sticky, and to agitate the mass by revolving it about ahorizontal .or inclined axis.

3.. The process of agglomerating fine iron ores or residues, which consists in passing the same through a: rotating kilnhaving a region in which the degree of temperature shall cause the particles thereof, due to the impurities contained therein, to fuse sufficiently to become semiplastic and sticky.

4. The process of desulfurizing and agglomerating fineiron oresor residues, which consistsin passing the same through a rotating kiln, in one part of which it shall be exposed to an oxidizing atmosphere at atemperature best. suitedfor. its desulfurization,,and in another part of which it shall be exposed to a temperature which shall cause the particles thereof; due to the impurities contained therein, to fuse suificiently to become semiplastic andsticky.

5. The process of agglomerating' fine iron ores-or: residues, which consists'in first moistening the mass and then subjecting the same to -a temperaturewhichshall cause the particles"ther.eof,.due to the impurities contained therein, tov fuse sufficiently to become semiplastic and sticky, and to agitate by rolling the mass when in the semiplastic state.

6. The processof agglomerating fine'iron oresor residueswhich consists in first moistening the mass and then passing the same through arotating kiln having aregion in which the degree of temperature shall cause the particles thereof, due to the impurities contained therein, to fuse sufficiently to become semiplastic and sticky..

7. The-process of desulfurizing and agglomerating fine ironores or residues which consists in first; moistening the mass and then passing the same'through a rotating kiln in one-part: of which it shall .be exposed to an oxidizing atmosphere at a temperature best suited forits-desulfurization and in another partof which it shall be exposed to atemperature which shall cause the particles thereof, due to the impurities contained therein, to melt .sufliciently to'become semiplastic and sticky.

DAVID BAKER. WILLIAM W. HEARNE. Witnesses:

BLANGHE F. MARTIN, LILLIAN M. HUDNUT.